1. Field of the Invention
This invention is related in general to data communications systems. In particular, the invention consists of a system for transmitting data from multiple-source logical macros to multiple-target logical macros utilizing a plurality of data buses.
2. Description of the Prior Art
Transmitting data between logical macros can be problematic as multiple-source logical macros may contend for available bandwidth. Traditionally, communication between logical macros occurs via point-to-point networks over through buses. In a bus-oriented communication system, only one source device may communicate with one target device at any given time. Various resource allocation algorithms have been employed to manage competition for the data bus, such as the banker's algorithm or the round-robin schema. In a round-robin environment, each requesting device is given a turn at communicating over the bus, regardless of the length or importance of the communication. Bottlenecks occur if short or high-priority messages get queued behind large and time-consuming transmissions.
In U.S. Pat. No. 6,633,994, Hofman et al. disclose a system and method for optimizing data transfers between devices interconnected by buses operating at different clocking speeds. Hofman discloses taking advantage of unused clock cycles by differentiating between devices operating at different clock speeds. However, additional hardware is required to detect the clock speed ratio and, if a difference is detected, a cycle control detection circuit is used to transmit data to high speed and low speed devices on separate buses. It would be advantageous, however, to have a system for improving data transmission performance without utilizing different clock frequencies.
In U.S. Pat. No. 5,909,559, So et al. disclose a technique for processor optimization utilizing unused instructions. So's approach includes dynamic balancing of computational resources, analyzing the scalability of system resources, reallocation of peripheral functions, modularization of resources, and performance modification by varying the available processor instructions. Additional hardware is required, including a digital-signal processor, to increase communication performance. Virtual service processors are utilized in a dynamic architecture to overcome bus latency issues by buffering data during busy cycles and transmitting data when the bus becomes available. This is accomplished by utilizing the virtual service processors to convert software tasks into threads and sub-tasks and implementing preemptive multi-tasking, allowing one task to be preempted to allow execution of another of higher priority. It would be advantageous, however, to improve data transmission without extensive preprocessing and reorganization of data.
In U.S. Pat. No. 4,974,153, Pimm et al. disclose a repeater interlock scheme for transactions between two buses including transaction and interlock buffers to prevent deadlock conditions. However, only one interlock read transaction may be transmitted to memory. If a second interlock read command is received, the memory returns a busy confirmation. This busy confirmation cannot be cleared until an unlock memory write signal is received. A deadlock occurs because the unlock memory write signal will not be detected until the second interlock read command is processed. Conversely, the second interlock read command cannot be processed until the unlock memory write clears the memory lock. Therefore, the unlock memory write is stuck behind the interlock read command. This problem is solved by using an interlock state bit and an interlock buffer residing in the repeater hardware. It would be advantageous to solve this problem, however, independent of system architecture and macros connected to the bus controller.